L2E: GroupBy always gets translated into Distincts, never Group By - sql-server-2008

Question

How can I get the Linq-to-Entities provider to truly perform a GROUP BY? No matter what I do, it always generates SQL that is far slower than an actual GROUP BY. For example:
var foo = (from x in Context.AccountQuantities
where x.AccountID == 27777
group x by x.StartDate
into groups
select new
{
groups.FirstOrDefault().StartDate,
Quantity = groups.Max(y => y.Quantity)
}).ToList();
translates to:
SELECT
1 AS [C1],
[Project4].[C1] AS [C2],
[Project4].[C2] AS [C3]
FROM ( SELECT
[Project3].[C1] AS [C1],
(SELECT
MAX([Extent3].[Quantity]) AS [A1]
FROM [dbo].[AccountQuantities] AS [Extent3]
WHERE (27777 = [Extent3].[AccountID]) AND ([Project3].[StartDate] = [Extent3].[StartDate])) AS [C2]
FROM ( SELECT
[Distinct1].[StartDate] AS [StartDate],
(SELECT TOP (1)
[Extent2].[StartDate] AS [StartDate]
FROM [dbo].[AccountQuantities] AS [Extent2]
WHERE (27777 = [Extent2].[AccountID]) AND ([Distinct1].[StartDate] = [Extent2].[StartDate])) AS [C1]
FROM ( SELECT DISTINCT
[Extent1].[StartDate] AS [StartDate]
FROM [dbo].[AccountQuantities] AS [Extent1]
WHERE 27777 = [Extent1].[AccountID]
) AS [Distinct1]
) AS [Project3]
) AS [Project4]
How can I get it to execute this instead?
SELECT
AccountQuantities.StartDate,
MAX(AccountQuantities.Quantity)
FROM AccountQuantities
WHERE AccountID=27777
GROUP BY StartDate
Again, note the lack of ANY GROUP BY in what's executed. I'm fine with EF optimizing things non-ideally but this is orders of magnitude slower, I cannot find any way to convince it to really do a GROUP BY, and is a major problem for us!

Answer 1

Use groups.Key instead of groups.FirstOrDefault().StartDate
var foo = (from x in Context.AccountQuantities
where x.AccountID == 27777
group x by x.StartDate
into groups
select new
{
groups.Key,
Quantity = groups.Max(y => y.Quantity)
}).ToList();